I work for ISS btw.
On Mon, 20 Sep 2004 18:49:25 -0400, David Maynor <dmaynor@gmail.com> wrote:
No guess. It's a simple recipe. Take one Tipping Point box, one
machine that is vulnerable to MS03-026, and a bit on coding knowledge
of rpc. I chose 03-026 because due to Blaster it should at be the one
exploit it could block. You then manually generate the bind request
carefully making sure the RPC frag size is so small that the target
guid is in two different packets. Something funny happens. You would
get system access and the Tipping Point box does nothing. Nada. Zip.
Zilch. While you are issuing commands like 'net user /add hacker' the
Tipping Point box stays silent. I scratched my head over this till I
realized that it happens because TippingPoint doesn't do protocol
parsing, it's the only explanation. Hardly the behavior for an award
winning IPS that writes its sigs for the vulnrebility and not the
exploitâ.supposedly.
On Thu, 16 Sep 2004 23:30:30 -0400, Tony Carter <tcarter@entrusion.com> wrote:
David,
Can you back your claim that IPS can easily be evaded by fragging
packets? Have you actually tested this or is it your guess?
-Tony
On Sep 12, 2004, at 12:29 AM, David Maynor wrote:
Yeah....I am gonna go ahead and disagree with you on some of these.
I have seen a lot of discussion about the differences between IDS,
IPS, and firewalls and the potential for convergence, but I do not
recall a discussion on the primary features that an IPS should have
out of the box.
I am thinking of:
- Flow Control - limitations on flooding, unused connections, etc...
Most of this should be handled by the signature base.
- Robust, ACURATE signature base
Only way to do this and not create tons of false postives is true
protocol parsing. This knocks out most IPS vendors like Tipping Point.
- Packet capture - no debate on how much before, as that has been
covered
- Pre-deployment network analysis tools to accelerate deployment
- Anomaly detection
Why? I have yet to see a system that is more than a parlor trick.
Anomaly based system are even easier to evade than sig based systems
that don't do protocol parsing.
What I would add is better tools for testing. Almost nobody grabs a
copy of Canvas from Immunity or Impact from Core and actually checks
what attacks are caught. Further more an even fewer number use modded
copies of public exploits to see if the claims made by vendors are
actually true. How many vendor's IPS implementation would actual catch
a MS03-026 exploit if you frag at the RPC layer at a size like 8
bytes?
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